NAPIT’s Technical Author, Richard Townsend, looks at omitting residual current devices (RCDs) in accordance with BS 7671: 2018+A2:2022, Regulation 411.3.3.
What have we been doing over the years?
When we look at Regulation 411.3.3, the option has historically been available to allow a designer to omit an RCD for additional protection on socket-outlets not exceeding 20 A.
Prior to BS 7671:2008+A3:2015, there was no requirement for a risk assessment, and supervision could be used to allow the use of non-RCD protected socket-outlets, not exceeding 20 A, or if labelling identified a particular piece of equipment that could only be used in that socket-outlet.
BS 7671:2008+A3:2015 introduced a requirement that the installation had to be non-domestic but retained the supervision or labelling caveats. This allowed the omission of RCDs supplying socket-outlets not exceeding 20 A only in commercial or industrial installations.
Some of these requirements were open to significant abuse and very often used to circumvent the installation of RCDs, where they were needed the most.
Why do we need to omit RCDs?
In the early days of RCD introduction, there were a number of instances where particular equipment types would cause the RCD to trip. Often referred to as ‘nuisance tripping’, we now call this ‘unwanted tripping’ because the RCD was operating as it should and detecting a potential fault.
Given advances in equipment and RCD design, many of those unwanted tripping issues aren’t here anymore. The usual culprits were fridges and freezers with a particular type of auto defrost mechanism, which newer designs have long since ironed out.
Another favourite was ‘the cleaner’s socket’, so a vacuum or floor polisher, for example, could be used without the threat of the RCD operating. In many cases, this was to protect against the RCD tripping outside of working hours, which made re-setting or fault-finding more difficult and could lead to expensive call-outs and an uncleaned building.
This type of omission is exactly why the Regulations have been refreshed, as this is not an acceptable reason to omit an RCD and leaves BA1 and BA3 persons at risk, especially in an out-of-hours scenario where there may be limited help in an emergency.
Was there a need for a change?
Unfortunately, even after the continual tightening up of Regulation 411.3.3, the national committee, JPEL 64, considered there was still widespread abuse and altered the Regulation again for BS 7671:2018+A2:2022.
There are now three indents instead of two, where additional protection by an RCD not exceeding 30 mA is required, which are:
1. Socket-outlets with a rated current not exceeding 32 A in locations where they are liable to be used by persons of capability BA1, BA3 or children (BA2, BA3)
2. Socket-outlets with a rated current not exceeding 32 A in other locations
3. Mobile equipment with a rated current not exceeding 32 A for use outdoors
There is now no mention of a domestic caveat, as all installations are treated the same, and the socket-outlet rated current has increased to 32 A, from 20 A.
The key part is that where any BA1, BA2 or BA3 persons are liable to use any such socket-outlets. These capability identifiers are as follows:
BA1 – Ordinary person (non-electrically skilled or instructed)
BA2 – Children
BA3 – Disabled persons
These categories are external influences, and a full description of them and other influences that may affect an electrical installation can be found in Appendix 5 of BS 7671:2018+A2:2022.
Can we still omit RCDs?
We can still omit an RCD, but only for indent (2); however, there must be a risk assessment for each socket-outlet that is to be omitted from RCD protection. Any risk assessment must be fit for purpose and adequate for the individual installation and its use. It’s for this reason the Client, duty-holder or user of the installation carries out any such risk assessment.
The Client or duty holder is key in the risk assessment as only they can initiate any control measures highlighted by the risk assessment, and only they can re-visit the risk assessment at regular intervals to ensure it is still fit for purpose.
That said, a skilled person (electrically) should be involved in the risk assessment process to give guidance on any dangers associated with not fitting an RCD and, in turn, the risk of any control measures that may be in place.
It should be noted that the skilled person (electrically) is not responsible for the risk assessment or its outcome; only the Client can decide if an RCD can be omitted, as it is their installation, and only they can control how it is used. An example of a risk assessment for this purpose can be seen in Fig 1.
A Client, or advisor to a Client, carrying out a risk assessment, should take careful note of indent (1).
If a socket outlet is in a locked, non-accessible location, or disconnected and cannot be used by a BA1, BA2 or BA3 person, and a process for ensuring this is highlighted as a control measure on any such risk assessment, then by definition, that part of an installation becomes indent (2) by way of a risk assessment.
In most electrical installations, we don’t see a need to omit RCDs, as most modern equipment is unlikely to cause an unwanted operation. This Regulation is geared for much more complex installations, where an RCD operating during a work evolution could have the potential to cause harm. We would expect some form of control measure, safe system of work, risk assessment method statement (RAMS), safety number, etc., to be in place during said work.
Can anyone be instructed?
Not under any circumstances can an ordinary person (BA1) be instructed in the use of the installation and therefore be deemed an instructed person (electrically).
This used to be a popular loophole which is now closed. Any employee who is an ordinary person (BA1) will remain in this category unless extensive training to electrician status has been undertaken.
So, to summarise…
We need to be clear that omitting an RCD protecting a socket-outlet, not exceeding 32 A, is a decision that can’t be taken lightly. A risk assessment is a complex process, and training and/or experience are needed to fully understand how to carry one out effectively.
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